Hydraulic method of mining coal and the like



1965 J. A. ANDERSEN 3,203,736

HYDRAULIC METHOD OF MINING COAL AND THE LIKE Filed 1961 2 Sheets-Sheet 1 3 ..|1iiii., x\ 16,

G D a INVENTOR. JAMES 4. 4N0E/85EN HYDRAULIC METHOD OF MINING COAL AND THE LIKE Filed Dec. 12, 1961 Aug. 31, 1965 J. A. ANDERSEN 2 Sheets-Sheet 2.

INVENTOR.

J/IMEJ 14 flrvozesan gmm 0 United States Patent 3,203,736 RAULIC METHOD OF NHFQING COAL AND THE LIKE Iames A. Andersen, 351 W. 80th, Seattle, Wash. Filed Dec. 12, 1961, Ser. No. 158,780 '4 (Ilaims. (Cl. 299-17) This invention relates to mining. More particularly it relates to improvements in the method of and means for mining coal, or similar substance, as contained in veins and stratified formations in the earth. The specific method of the mining operation being characterized by use of novel means for cutting, dividing and disintegrating the vein or formation by means of an extremely high pressure water jet of small diameter discharged against the exposed face of the coal vein.

It is the principal object of this invention to provide a method of hydraulic jet mining that is economically practical; that is safe, and which can be carried on at a relatively low labor cost in comparison with costs incurred in ordinary coal mining operations. Furthermore to provide a method that may be carried on without blasting and the dangers incident thereto and without production of explosive gases, dust or other products that are detrimental to life in coal mining operations or obnoxious or injurious to the workmen.

Another object of the invention is to provide a method of mining that employs hydraulic jets of water of unusually small diameter, delivered under exceedingly high pressure and in a manner designed to separate the coal eing mined into chunks or blocks and to similarly cause its disintegration into pieces or sizes suitable for conveyance by cars, conveyor belts, or the like, from the mine.

In accomplishing the above mentioned and other objects of the present invention, 1 have provided an improved method of operation and improved details of construction of the mechanical means for carrying out the hydraulic method of mining as illustrated in the accompanying drawings, wherein:

FIG. 1 is a sectional view of a body of earth containing a vein of coal or other material to be mined, and showing schematically an arrangement of tunnels, chutes and passages for use in practising the present methods.

FIG. 2 is a cross-sectional view through the coal vein taken in the plane of line 2-2 in FIG. 1.

FIG. 3 is an enlarged view illustrating the manner of hydraulic jet mining.

FIG. 4 is an enlarged longitudinal section of a preferred form of a nozzle tip employed in the present operation.

While the present method and means may be applicable for use in mining various material, its present disclosure relates particularly to the mining of a pitching vein of coal, but with the understanding that the method and apparatus may be modified in accordance with requirements of the particular material and direction of the vein without departing from the invention.

Referring more in detail to the drawings:

In FIG. 1, a body of earth has been shown to contain a vein 12 of what will here be considered to be coal. This vein might be in a pitching or in a near vertical position, as illustrated, or it might be a horizontal vein.

For the present operation, the body of earth 10 has been shown to be formed with a horizontal gangway or tunnel 15 that extends horizontally through the pitching vein or coal formation 12 and from this gangway tunnel a plurality of spaced, vertically directed chutes or shafts 16 are formed, leading upwardly within the vein. The chutes 16 divide the vein into blocks or units 18 which 3,203,736 Patented Aug. 31, 19 65 ice are, preferably, from 30 to 50 feet in length and widths that are in accordance with the transverse thickness of the coal vein or stratification at the location of any particular block.

The horizontal passage 17 is generally referred to as the counter and its primary purpose is to serve as a ventilation passage. It will be noted that the chutes are blocked off between the gangway 15 as at 16x and counter 17 except at the center chute. The counter is interconnected with a generally vertically disposed passage 1711 which leads to the surface. An exhaust fan not shown is positioned at the surface entrance of the passage 17a. The combination of fan and passage provides the desired ventilation of mining area.

The section of the coal vein illustrated in FIG. 2 is vertically disposed but in actual coal veins, the veins are normally at various angles to the perpendicular. The earth of rock at lower side of the vein, as at 12a if the vein were at an angle, is normally referred to as the footwall. The earth or rock at the upper side 12b is referred to as the hanging wall.

Leading upwardly from the left hand end of the gang way or tunnel 15, as seen in FIG. 1, is a continuing tramway 15x leading to the surface to provide for the movement or conveyance of the transporting cars or vehicles 19 used for transporting mined coal to a place for the surface storage of mined material.

At the lower end of the tramway is a water pump 15y which is provided for collecting the water employed in the hydraulic jet mining as will presently be explained The hydraulic mechanism employed in the present operation includes an electric motor and a hydraulic pump to which the motor is operatively connected, the com: bination being designated by reference numeral 25. The motor, pump and all necessary controls are mounted on a car or carrier 27 which may be conveniently employed in the gangway 15. Water is supplied through a hose 29 to the pump from a source of supply on the surface. Leading from the pump is a flexible, reinforced conduit 23 which is of the desired size and construction to satisfactorily perform the hydraulic mining.

The nozzle, shown in FIG. 3, comprises a metal tube 33 of suitable length, to one end of which the discharge end of conduit 23 is connected. At is outer end the tube 33 is equipped with the nozzle tip 35 of this invention which is best shown in FIG. 4 to comprise a tubular body that is threaded at one end into the pipe or tube 33. The nozzle tip 35 is formed with an axial passage 36 that tapers to a mall diameter axial bore, The passage 36 tapers for a distance of approximately 1 /2 to 2 inches from a diameter of approximately /2 inch at its receiving end to a uniform bore 38 of a diameter between to inch. The bore 38 is from inch to 1 /2 inches in length. Water is delivered under pressure of from 2000 pounds per square inch to 10,000 pounds per square inch. The pump now employed has a capacity of 19.2 gallons per minute, up to 10,000 pounds pressure, while using a nozzle tip of up to .012 of an inch. The pressure employed and the size of the nozzle will vary depending upon the texture and hardness of coal in a particular vein or area.

The formation of the tramway, gangway, counter and chutes may be made by drilling, blasting or by hydraulic jet cutting and breaking up of the vein. After these passages have been provided the cutting and removal of the coal from the mine is as follows:

The mining operations may start at any desired point on blocks or divisions 18 as formed between the shafts and progress upwardly as illustrated in FIGS. 1 and 3. As each block of material is cut and disintegrated by the action of the hydraulic jets, the pieces formed are con- (.9 veyed directly or indirectly into the vertical shafts or chutes 16 and allowed to fall therethrough into the gang- Way 15 for loading into the coal cars or transporting vehicles, 1-9 to be moved to surface storage. This gravity system of loading results in a great saving in labor and greatly expedites the mining operation.

The water also flows by gravity from the area of mining through the passages and down the chutes to the gangway where a ditch or trough is provided to carry the water to the sump.

"For the cutting and disintegrating of the blocks or divisions 18, I employ one or more hydraulic jets 40 that are caused to be discharged under the exceedingly high pressure disclosed, through the nozzle tips 35 applied to the ends of nozzles as seen in FIG. 3.

It has been found to be quite practical and also advantageous to use a nozzle tip with dimensions as above disclosed when the water is supplied thereto under a pressure of from 2,000 to 10,000 pounds per square inch. It has also been found that a passage tapered at a 6 angle leading therein to the orifice entrance, as shown in FIG. 4 is advantageous and practical. When larger diameter orifices are used, it is desirable to form a rounded entrance to the orifice.

The present method of mining is based upon the proven fact that by directing a high pressure jet of water against the face of a block 18 of coal, the coal at the proximity of the point of impact of the jet, disintegrates and a hole, channel or groove will be opened up in the block or vein and this may be formed to any practical width, depth and length.

The coal which forms the vein is mineralized vegetable matter which has decomposed and compacted under terrific pressure-s. The material is so deposited that it contains infinitesimal structures which are separated by fractures which run in all directions. The extremely small stream of water directed at the face or exposed surface of the coal vein under the very substantial pressure as above indicated, disintegrates the coal at the point of impact.

The preferred method of operation for removal of coal from the vein, after the tunnels, chutes and passages have been prepared therein, is to begin at a desired location on a block 18. First the side seam of the vein is cut along the footwall of the block as at line b in FIG. 2. Then a horizontal channel or cut is formed at a lower level across the bottom portion of the unit to be removed, to a depth of, for example, from three to four feet, and another cut is made horizontally in the block about three to four feet above the lower cut and then a vertical cut is made at a distance of from 3 to 4 feet from the vertical cut on line b. Thus, the block of coal is cut free on three sides and this may fall of its own weight or be readily forced free from the unit by pressure of water injected into the top cut or side cut. In this same manner, chunks or units may be freed from the block upwardly in succession as is illustrated in FIG. 3.

It is to be understood that there is no fixed order in the manner of forming or spacing the cuts to define the chunks or unit cut, or in the depth of cuts made; this being determined by the character of the material being mined and in the conditions of the vein and surrounding rock or soil. If desired, relatively small chunks or units may be removed. The exact procedure of separation of coal from the vein will vary and is at the discretion of the operator.

It is acknowledged that relatively high pressure jets or streams of water have heretofore been employed for cutting or separating various substances, however, to my knowledge, no one has previously used pressures of the magnitude herein specified for mining coal or similar material. I have determined by numerous experiments the minimum pressures required and the specific details of construction of the nozzle which. produces the desired results. In present experiments, employing my method,

in an actual coal mining operation, it has been determined that the productivity has increased from an average of 12 tons per man day to over 20 tons per man day. This is a comparison between the conventional, long used methods of mining and the hydraulic jet method of mining which is the subject matter of this application. The significance of this substantial increase in productivity will be even more apparent when it is understood that approximately 70% of the cost of mining coal is labor cost.

Of equal importance to the productivity advantage is the safety advantage which is inherent from the use of the hydraulic jet method as compared with the conventional drilling, blasting and mechanical .coal mining methods or equipment presently being used. All of these present methods create substantial dust and gases whereas hydraulic jet mining completely eliminates this problem. This is a definite advantage to the health and well being of the miners and it greatly reduces the possibility of explosions. The safety factor is further improved in that by the hydraulic jet system, the footwall and hanging Wall are not disturbed nor are the overlying or underlying strata broken or cracked.

Other advantages are found in the reduced cost of equipment and supplies. No expensive mechanical devices are required. It eliminates the cost of blasting powder and caps. Also, it permits selective mining in that only portions of a vein may be removed so that strata of undesirable material may be left in the ground undisturbed. It minimizes the breakage and fines in the coal which is mined and produces a much larger percentage of coarse coal or larger chunks which sells at a higher price. Drilling and blasting produces a substantial percentage of small pieces of coal and dust.

It is an important feature of my invention to use a nozzle with a discharge orifice of a minimum diameter. This is important because it reduces the quantity of water required and the smaller streamis more effective in cutting or disintegrating than a larger stream of the same pressure. The water must be provided and ultimately removed so that it is obviously advantageous and desirable to use a minimum quantity of water which is sufficient to perform the required result. The quantity of water is also significant in that it will be absorbed by the coal and it is desirable to reduce the water absorption as much as possible.

Although I have described the mining process primarily as related to a pitch seam coal vein, it is to be understood that my invention is not limited to any particular strata or formation. The method may also be employed in flat seam mines and on materials other than coal.

What I claim as new is:

1. The method of mining coal or the like comprising directing a hydraulic jet of not greater than one-fourth inch in diameter at its point of origin to its point of contact and discharged under a pressure of net less than 2000 pounds per square inch against the vein of coal and progressively moving the jet and so directing it as to cut a plurality of channels therein in spaced relationship and to substantial depth then effecting the breaking free of the coal between adjacent channels by the applying pressure of the hydraulic medium in the channels.

2. The method recited in claim 1 wherein the pressure applied for the discharge of said hydraulic jet is within the range of from 2000 to 10,000 pounds per square inch.

3. A method according to claim 2 wherein the diameter of the jet ranges between one-thirty second and nine-sixty fourths of an inch.

4. The method of mining coal or the like comprising directing .a hydraulic jet of approximately inch in diameter between its point of origin and its point of contact and discharged under a pressure between 2000 and 10,000 pounds per square inch against the vein of coal and moving the jet in such manner as to cut a channel therein to define blocked off areas, then applying the pressure of the hydraulic medium as supplied by the jet into the chan- 5 6 nels to break the material of the blocked-0E area free OTHER REFERENCES from the Bureau of Mines Information Circular 7887, Mining and Transporting Coal Underground by Hydraulic Meth- Refmnces C'ted bythe Examme' ods: A Literature Survey, by William T. Boyd, 1959,

UNITED STATES PATENTS 5 United States Government Printing Ofiice. 2,148,495 2/39 Osgood. Mining Congress Journal, January 1961, pages 5254. FOREIGN PATENTS BENJAMIN HERSH, Primary Examiner.

773,344 9/34 France. 

1. THE METHOD OF MINING COAL OR THE LIKE COMPRISING DIRECTING A HYDRAULIC JET OF NOT GREATER THAN ON-FOURTH INCH IN DIAMETER AT ITS POINT OF ORIGIN TO ITS POINT OF CONTACT AND DISCHARGED UNDER A PRESSURE OF NET LESS THAN 2000 POUNDS PER SQUARE INCH AGAINST THE VEIN OF COAL AND PROGRESSIVELY MOVING THE JET AND SO DIFECTING IT SO AS TO CUT A PLURALITY OF CHANNELS THEREIN IN SPACED RELATIONSHIP AND TO 